Leeson initially was very successful in speculative trades, making huge profits for Barings and ensuring his upward mobility. Unfortunately, Leeson lost his touch as his speculative range increased. Leading up to 1995, he had been hiding losses from bad trades in a secret account. Leeson was able to accomplish this because of a management flaw in Barings that gave him the responsibility of double-checking his own trades, rather than having him report to a superior. Instead of reigning in his speculative gambles, Leeson continued to play increasingly bigger odds in an attempt to recover lost money.

Ironically, the trade that undid Leeson and the 200-year-old bank was one of his more conservative positions. Leeson placed a short straddle on the Nikkei, guessing that the exchange would remain stable overnight, neither going up nor down by a significant margin. Normally, Leeson would have been safe in such a position, but the earthquake in Kobe caused a sharp drop in the Nikkei and other Asian markets.

Faced with huge losses, Leeson panicked and attempted to offset the losses with increasingly desperate, short-term gambles that were based on the rate of recovery of the Nikkei. Sadly, the severity of the earthquake squashed all hopes of a rapid recovery. Leeson fled the country, but eventually he was arrested in Germany. Barings, having lost over $1 billion -more than twice its available capital - went bankrupt. Leeson wrote his aptly titled Rogue Trader while serving time in a Singapore prison. Leeson held the world title for losses due to unrestricted trades for over a decade, but he was eclipsed on January 25, 2008 when French bank Societe Generale announced that a rogue trader had lost more than $7 billion.